1. Field of the Invention
The present invention relates generally to tanks used for flammable or explosive fluids such as fuel tanks, including gasoline, diesel fuel, and LPG gas; and particularly this invention relates to tanks employing a filler mass insert to aid thermal distribution to suppress explosion or to boost vaporization.
2. Description of the Prior Art
In a typical tank application, such as a propane or LPG tank, there is generally encountered a metallic tank wall designed to contain the fuel under pressure, with associated valves and connections at one end to access the contents thereof. During normal operation of a vaporization system the liquid fuel vaporizes in the tank under ambient heat to provide an operating pressure under which the vapor is withdrawn through the tank valve. Consequently, the pressure of the system falls as a result of use and the tank will exhibit decreased function until the liquid temperature is raised.
Similarly, in liquid fuel applications, where heat is applied locally to the tank (such as in a fire), the liquid proximate the hot spot will boil and increase the vapor pressure within the tank and possibly ignite. Prior attempts to neutralize the explosion tendencies of the tank have included providing an expanded aluminum foil mesh as a filler mass insert within the tank.
Improvements in filler mass design have been directed to preventing nesting of the mesh by reversing alternate layers in a roll. Nesting occurs where the mesh pattern of adjacent layers settle against each other in a mating relation. This anti-nesting system is described in the 1979 patent issued to Szego, U.S. Pat. No. 4,149,649, as applied to explosion suppression in fuel tanks, although the technique had been employed for many years prior in the filter industry. This filter application has been the principal use of such expanded foil. Even with the anti-nesting technique of Szego, the foil mesh collapsed and compressed during use and its effectiveness diminished. Recently, U.S. Pat. No. 4,673,098, issued to Fenton et al., dramatically improved the thermal conductivity and reduced the compression tendency by using adhesive to secure the filler mass within the tank. Notwithstanding these developments the need continued to exist for the development of a filler mass and tank apparatus design which would be more economical to manufacture, allow for greater fuel volume, and provide greater thermal distribution.